Vacuum desolder implement



United States Patent inventor William S. Fortune 14250 Dearborn St.,Panorama City, California 91402 Appl. No. 712,748

Filed March 13,1968

Patented Dec. 1, 1970 VACUUM DESOLDER IMPLEMENT [56] References CitedUNITED STATES PATENTS 3,393,854 7/1968 Fortune 228/20 PrimaryExaminer-John F. Campbell Assistant Examiner-Robert J. CraigAttorney-Daniel T. Anderson ABSTRACT: The specification discloses asmall, hand held, cylindrical, vacuum stroke tool for removing moltensolder. A trigger mechanism carried by the cylindrical'body may hold aspring-loaded piston near the tip, solder inlet end of the tool. Ahollow, cylindrical, cocking plunger extends out of the opposite end ofthe body and is displaceable axially to push the piston forwardly untilit engages the trigger mechanism. The cocking plunger, coupled to thepiston by an axially-tensive spring is then pulled rearwardly and lockedin place. When the trigger mechanism is actuated to produce the solderremoving vacuum stroke, the piston flies back and strikes the forwardend of the cocking plunger. The piston and the cocking plunger areconstructed so that the indicated impact unlocks the cocking plungerthus enabling it to be moved forwardly for a subsequent cocking action.

Patehted Dec. 1, 1970 llri William S- Fortune INVENTOR ATTORNEY VACUUMDESOLDER IMPLEMENT BACKGROUND or THE INVENTION although the presentinvention finds particularly useful application in the field ofsoldering, desoldering, and rewiring? in an electronic laboratory,maintenance shop, factory or hobbyist bench; and although in the causeof brevity and clarity, most of the following discussion and descriptionof examples of the invention are directed theretoward, it is expresslyto be' understood that the advantages of the invention are equally wellmanifest in other fields,.as indicated above, where a mobile substanceis to be removed from a limited or particular portion of an object.

2. Background of the Invention In the electrical arts as mentioned, itis often desired to desolder an electrical connection such as, forexample,a wirewrapped terminal, awire to'circuit-board eyelet, or thelike. The removal from the connection of the molten solder withoutdropping or splattering it onto other portions of the equipment isgenerally essential. Blowing or shaking the molten metal away, istherefore not an acceptable practice; and the high surface tensionassociated with the solder precludes, at least practically, its removalby other than vacuum techniques. Furthermore, the problem isaggravatedby the requirement that the'solder be removed without'application ofcool or heat conductive means before the mechanical connection such as awire-wrapped terminal may be taken apart. 7

Various nonportable central vacuum systems and highly portable andefficient hand held vacuum stroke tools as described in the referencedpatents have successfully solved a number of the prior; art desolderingproblems. The device shown in the first of the above patents includes athin-walled cylinder housing a spring-loaded vacuum-producing pistonwhich is connected to an axial-cocking plunger shaft which passesthrough a bushing at the upper or rearward end of the cylinder and isterminated'by a knob. The bushing includes a.

trigger mechanism which cooperates with the cocking shaft to hold thepiston, against spring force, near the forward solder inlet tip enduntil the trigger is depressed. When thusly actuated, the piston isforced by the spring to flyback" to the the molten solder therewithin.The apparatus may then be recocked for a subsequent vacuum stroke.

As indicated, theseclevices have advanced the state of the 1 upper,bushing end of the cylinder body. The resulting vacuum stroke impulse ofairflow through the tip end draws art and have solved certain aspects ofthe desoldering problems outlined; however, they suffer from somedisadvantages in some applications due to the recoil or flyback actionof the piston-cocking shaft-knob assembly during the vacuum stroke. Thecocking shaft which functions as a connecting rod between the piston andthe cocking knob must be heavy enough and strong enough to cock thepiston against a relatively strong loading spring. Also the cocking knobmust be large enough and soft enough for comfortable repeated cockingcycles by the hand. of the operator. These criteria cause the flybackmass to be relatively large compared to the thin-walled cylindricalhousing body; consequently, the outer housing suffers a recoil causing adeflection of the solder inlet tip away from the location of the moltensolder.

Another disadvantage'of the abrupt flyback of the shaft and knob is thatthe eye of the operator during the vacuum stroke is typically disposednear thereto in a position causing risk of eye impact injury.

some of these disadvantages have been overcome by the teachings of thelatter of the referenced patents; however, the devices constructed inaccordance therewith are typically somewhat complex and costly.

It is, accordingly, an object of the present invention to provideimproved desoldering apparatus which is not subject to these and otherdisadvantages and limitations of the prior art.

It is another object to provide such apparatus which, while providing ahigh amplitude of impulse airflow, has no exposed flyback portion and avery low inertia associated with the flyback portions thereof causing anegligible deflection of the tool during its vacuum stroke.

It is another object to provide such apparatus which is low in cost andsimple, rugged and reliable in its structure and performance.

It is another object to provide such apparatus which, after each vacuumstroke, is automatically fully enabled for recocking.

It is another object to provide such apparatus in which the profile ofairflow versus time during the vacuum stroke is adjustable over a widerange.

It is another object to provide such apparatus in which the operatorshand may be disposed to hold the implement close- Iy to its tip'end inpencil holding fashion, for improved precision use thereof.

It is another object to provide such apparatus which is automaticallyself cleaning with each cocking cycle.

SUMMARY or THE INVENTION Briefly, the above and other objects of theinvention are achieved in accordance with the structural aspects of anexample of the invention which includes a handheld, thin-walledcylindrical body having a forward, solder inlet tip end and a rear,bushing end. A piston is disposed within the cylindrical body and itsrapid, spring-propelled displacement rearwardly causes a solder-pullingflowof air inwardly through the inlet tip.

A cocking plunger supported by the bushing end is of the character todisplace the piston forwardly to a position near the tip end where atrigger mechanism carried by the cylindrical body holds it securelyagainst rearward motion until the trigger is actuated to release it. Thecocking plunger is then pulled rearwardly for approximately the lengthof the cylindrical body. A tension spring is connected between thepiston and the cocking-plunger whereby such rearward displacement of thelatter, a strong rearward force is applied to the former. The cockingplunger and the bushing are of the character to achieve a locking actionfor the cocking plunger'to hold it axially from being pulled forwardlyby the tension spring, this locking mechanism-being of the character tobe automatically unlocked when impacted by the piston during itsflybackcycle upon release by the trigger. The implement, by cooperativeinteraction of these means is thereby totally enabled automatically forrecocking in preparation for an immediately subsequent vacuum stroke.

Further details of these and other novel features and their principlesof operation and cooperation as well as additional object and advantagesof the invention will be made apparent and be understood from aconsideration of the following description when taken in connection withthe accompanying drawing which is presented by way of an illustrativeexample only.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinal sectional viewof an example of a vacuum desolder implement constructed in accordancewith the principles of the present invention;

FIG. 2 is an enlarged sectional view of a portion of the struc- I tureshown in FIG. I;

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT With specific referenceto the FIGS. in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion only and arepresented in the cause of providing what is believed to be the mostuseful and readily understood description of the principles andstructural concepts of the invention. In this regard, no attempt is madeto show structural aspects of the apparatus in more detail than isnecessary for a fundamental understanding of the invention. Thedescription, taken with the drawing will make it apparent to thoseskilled in the mechanical arts how the several forms of the inventionmay be embodied in practice. Specifically, the detailed showing is notto be taken as a limitation upon the scope of the invention which isdefined, rather, by the appended claims forming, along with a drawing, apart of this specification.

In FIG. 1, the example of the desolder implement l illustrated includesa thin-walled metal cylindrical body 12 having a forward, tip end 14 anda rear, bushing end 16. A tip fitting member 18 is shown removablysecured within the forward end 14 and includes, for that purpose, alarge diameter, short, cylindrical retainer portion 20 and a retainingshoulder portion 22. A small diameter portion 24 extends forwardly fromthe main portion of the fitting member and a solder inlet, air duct 26extends axially through the entire fitting.

A piston body 28 is disposed axially sliding within the cylindrical body12 and includes an O-ring piston ring 30 retained within a retaininggroove 32 which has it conically tapered base surface 34 concentric withthe axis of the body 12 and having a rearwardly convergent configurationas shown. The taper permits forward travel of the piston body withminimum impedance with regard to sidewall friction and sealed air pumpeffects, while automatically providing a tight air pump seal in itsrearward travel because the frictional drag draws the piston O-ringrelatively axially forwardly to maximize its diameter and air sealrelation with respect to the inner wall of the cylindrical body 12.Further details of the piston body 28 are discussed below in connectionwith the more detailed view of FIG. 2. It may be noted here, however,that the piston body may be fabricated by molding it from a plastic andthat a tip self cleaning rod member 36 extends axially through theentire piston body for automatically cleaning the .duct 26 during eachcocking stroke. The rod member 36 may be secured to the piston body byan opposed pair of self-threading nuts 38, 40, the latter being utilizedalso to retain the forward end of a tension spring shown below in thesubsequent FIGS.

A hollow cocking shaft 42 is disposed within and retained and guided bya rear bushing member 44. The cocking shaft may be pushed forwardlyinwardly to its position shown for cocking the piston member 28 in itsforward position as shown. Throughout its axial travel, the cockingshaft is guided by an elongate guide groove 46 and its relationship withan angularly fixed guide pin 48 firmly retained by the bushing member44. The forward end of the guide groove 46 is terminated in a short,right-angle locking portion 50.

The rear end of the cooking shaft 42 is shown fitted with a cocking knob52 which is frictionally resistively rotatable with respect to thecocking shaft whereby the airflow rate from therewithin may becontrolled by the degree of registration between a valve opening 54through the cocking knob and an axially alined like opening 56 formedthrough the sidewall of the cocking shaft as shown.

The bushing member 44 includes a rear, full diameter portion 58 and aforwardly extending thin-walled portion 60 firmly retained within therear portion 16 of the cylindrical portion 12. As shown below, theangular disposition of the bushing member 44, its guide pin 48, and itsforwardly vectored end portions 62 is fixed with respect to the body 12.

Referring to FIG. 2 the piston body 28 is seen to include a transversebore 64 for retaining a trigger member 66 and a trigger compressionspring 68; The trigger member 66 is retained within the bore 64 by theaxial passage therethrough of the tip-cleaning-rod member 36 and itsrelationship with a vertically elongated rod-receiving aperture 70formed'transversely through the trigger member 66.

The vertical elongation of the rod-receiving aperture 70 ischaracterized bypermitting depression of the trigger member into thebore 64 against the compression spring 68 so that the piston body 28 maytravel axially freely within the body 12 except when the trigger member66 projects outwardly, as shown in the FIG., through a trigger-engagingaperture 72 formed in the forward portion 14 of the body 12. The upper.or outer, end ofthe trigger member 66 is rounded as shown to facilitateits release against the outward force of the spring 68 for rearwardtravel of the piston body 28. I

The forward edge 74 of the trigger aperture 72 may be canted outwardly,as shown, whereby the piston body may be freely pushed furtherforwardly, when desired, for ejecting the tip fitting 18 as for itsreplacement or for cleaning the tip fitting 18 as for its replacement orfor cleaning or lubricating the barrel of the body 12. Asindicatedearlier, the retaining nut is, in this example, utilized forsecuring the forward end of the main tension spring 76.

The trigger-engaging aperture 72 may be sealed against intrusion of airduring the vacuum stroke by a disc 78 of rubber or neoprene. However, ithas been found practical in some embodiments to delete the sealing discbecause the trigger finger of the operator inherently substantiallyseals the passage during piston flyback.

' The rear portion ofthe piston body 28 is shown horizontally relievedto form a female indexing trough 80 which is engaged by the forwardlysimilarly vectored end portion 82 (see FIG. I of the cocking shaft 42during the cocking stroke and at the end of the flyback vacuum stroke asdescribed subsequently herein. 1

In FIG. 3, the implement is shown-in exactly the same disposition as inthe previous FIGS. except that the cocking shaft has been withdrawnrearwardly as far as the fixed guide pin 48 in the guide groove 46 willpermit. The cocking shaft is then rotated a few degrees counterclockwisewhereby the locking portion 50 of the groove is engaged lockingly by thepin 48 as shown. In this position the tension spring 76 is in itsmaximum energy storage disposition stretched between the piston body 28and the rear end 84 of the cocking shaft. 42. It may be noted that thespring is thusly stably held by virtue of the trigger member 66 inengagement with the aperture 72 and the locking engagement of the guidepin 48 with the guide groove portion 50. Depression of the trigger bythe operators finger tip will cause the flyback of the piston body withresultant impulse flow of air inwardly through the duct 26 of the tipfitting 18. I

Referring to FIG. 4, the schematic, partially axially-exploded viewillustrates the angular relation of the forwardly vectored portions 82and 62 ofthe cocking shaft 42 and bush ing member 44, respectively, withrespect to each other and the indexing trough 80 of the piston body 28.The vector trough portions 62, 80 are angularly alined while thepartiallyrotated cocking shaft vectored portions 82 are angularly cantedwith respect to both. The forward extension of the vectored portions 62,82 is approximately equal, however, so that upon flyback of the pistonbody 28, its indexing trough 80 first impacts the portions 82 of thecocking shaft and rotates the shaft until angular alinement of all threeelements is achieved.

In the latter relation, as illustrated in FIG. 6, the cocking shaft isautomatically enabled for immediate recocking of the piston body sincethe guide pin 48 is no longer engaged by the groove portion 50 but is,in fact in alinement again with the main guide groove portion 46.

With brief reference back to FIG. 5, the concentric relationships of theseveral elements of the implement are illustrated with respect to thereference lines 5-5 of FIG. 3. The outer metallic body 12 isshown'grooved at 86 to receive and angularly index the guide pin 48which is permanently held by the thin-wall portion 60 of the plasticbushing member 44. The radially inner tip ofthe pin 48 is shown inengagement with the locking portion 50 of the guide groove 46 formed inthe hollow cocking shaft 42 within which is shown disposed the tensionspring 76 and through which may be seen the cocking knob 52.

There have thus been disclosed and described a number of the structuralaspects of an example of a vacuum stroke desolder apparatus whichachieve the objects and exhibit the advantages set forth hereinabove.

I. claim:

1. Vacuum stroke desoldering apparatus comprising:

a tubular body member having a rear bushing end and a forward tip end;

tip end means carried by said body member contiguously to said tip endand having a solder inlet duct formed therethrough in airflowcommunication between the external environmental atmosphere and theinterior of said tubular body member;

bushing means carried by said body member contiguously to said rear endthereof;

piston means disposed within said body member and being longitudinallyslidable therewithin in an air-driving relation with respect to saidairflow through said solder inlet duct;

cocking shaft means carried by said body member and having a length ofthe order of that of said body member and including a rear outer enddisposed rearwardly of said bushing means, and a forward end disposedinternally of said body member and forwardly of said bushing means;

spring means carried by said body member for urging said piston meansand said cocking shaft means toward each other;

cocking shaft holding means carried by said body member for holding saidcocking shaft means rearwardly and havexternally actuable shaft latchingmeans, and

internally actuable shaft unlatching means; and

piston holding means carried by said body member for holding said pistonmeans forwardly therewithin and having:

internally actuable piston latching means, and

externally actuable piston unlatching means, said internally actuablecocking shaft unlatching means including impact responsive meansengageable with said piston means for causing said unlatching when saidimpact means is engaged by said piston means during its rearward vacuumstroke travel.

2. The invention according to claim 1 in which said tip end meansincludes a tip end fitting which is removably carried by said bodymember coaxially therewith and through which said solder inlet duct isconcentrically formed as an axial bore.

3. The invention according to claim 1 in which said cocking shaft meansis carried coaxially by said body member.

4. The invention according to claim 1 in which said externally actuablecocking shaft latching means and said internally actuable cocking shaftunlatching means are of the character structurally to be actuated byrotation by small fractions of a revolution of said cocking shaft meansabout the axis of said tubular body member.

5. The invention according to claim 4 in which said externally actuablecocking shaft latching means is of the character to latch responsive tomanual rotational force applied to said rear outer end of said cockingshaft means.

6. The invention according to claim 4 in which said internally actuablecocking shaft unlatching means is further of the character to unlatchresponsive to rotational force applied thereto by said piston means.

7. The invention according to claim 4 which further includes guide pinmeans and guide groove means carried one by said body member and one bysaid cocking shaft means and being of the character structurallycooperatively to control the angular disposition, with respect torotation about said axis, of said cocking shaft means as a function ofits displacement axially with respectto said body member.

. The invention according to claim I m which said internally andexternally actuable, respectively piston latching and unlatching meansincludes a trigger member carried by said piston means and atrigger-receiving aperture formed in said body member contiguously tosaid forward tip and thereof; said trigger member being of the characterto be resiliently laterally movable outwardly for self engagement inlongitudinal piston holding relation with the edges of said aperture,and for manual selective disengagement therefrom.

9. The invention according to claim 4 in which the rear portions of saidpiston means are formed to provide a cocking shaft engaging troughdisposed laterally thereacross.

10. The invention according to claim 9 in which the forward portions ofsaid cocking shaft means are vectored forwardly in a manner structurallyto engage at least partially congruently and rotationally drivably saidtrough of said piston means.

